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B&S 252707 / 0648-01 VERY Hard Starting


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04-15-09, 06:59 PM   #1  
B&S 252707 / 0648-01 VERY Hard Starting

Hello All,

I'm new to the forum and I'm having starting issues with my riding mower. It has the B&S model #252707, type 0648-01, 11 HP, 400cc engine.

I bought the mower used last summer (previous owner claimed it's an '88 model - Bluegrass Classic). It ran great all season and never let me down minus a broken deck mount, which I fixed.

This season is a different story. It started fine a few weeks back after sitting all fall and winter under my deck. I mowed a small area with it just to see how it would perform. The following week when I intended to finally mow the entire yard, it started fine. I moved it to level ground to check the oil level and add fuel. After that it would not start. I even ran the battery down trying to crank it.

A few days later after removing the spark plug (and charging the battery) I was finally able to get it started. It was acting as if it was flooding. The spark plug kept getting wet with gas. Once I did get it started, I really had to fenagle with the throttle to keep it running. I mowed the yard and decided to shut it off and try to start it right back up.... Didn't happen! I did "adjust" the screw in the bottom of the fuel bowl, which helped some while mowing.

I'm pretty sure I have a fuel delivery issue. It's getting spark and air. I've heard and read that the ethanol fuel now sold in most places can wreak havoc on small engine carbs. Could this be my problem? Do I simply need to rebuild the carb? What typically causes these symptoms? This thing used to start after only a couple of cranks.

Any info is appreciated.

Thanks in advance.

300Deluxe

 
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04-15-09, 07:57 PM   #2  
I'm thinking the float is ""Gas logged"" & isnt floating any more &/or the float needle has some trash in it,.. Check the oil for over full or a fuel smell & don't run the unit with fuel in the oil "till you fix it..You may only need a carb kit...Roger

 
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04-16-09, 04:43 AM   #3  
Thanks for the reply hopkins. Are carb kits very expensive for these?

 
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04-16-09, 06:18 PM   #4  
Fast1, It's like "waterlogged" only it's full of gas, not water..
300Deluxe, I don't think kits are very expensive, but you may also need a float which is not included in the kit.. You're local small engine dealer will give you the price since you have the engine numbers for him to look them up.. Roger

 
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04-16-09, 10:17 PM   #5  
Does the oil smell like gas?


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04-17-09, 04:43 AM   #6  
The oil doesn't smell like gas. I priced a rebuild kit yesterday - $22.95. I'll rebuild the carb and go from there.

Is there an online source illustrating (or explaining) how all of the various screws should be adjusted? i.e. mixture screw, and high-speed valve? I know how to get them in the same position they currently are after the rebuild, but I'd like to see how they were positioned from the factory.

On an unrelated note: How would a person go about adjusting the governor on these engines? When the mower is at full throttle with no load on the engine, the revs go WAY up. I'm assuming the governor isn't working properly.

Any insight?

Thanks in advance.

 
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04-17-09, 09:55 PM   #7  
Set the throttle wide open, then loosen the governor clamp and rotate the governor rod the same direction it would go to open the throttle until it stops, then while holding it in place, tighten the clamp.


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04-18-09, 04:52 PM   #8  
Hey Guys,

I disassmebled the carb yesterday and soaked it in cleaner overnight. I re-assembled it today and installed it on the engine.

Unfortuneatly, as soon as I hooked the gas line up, gas was running back into the air horn (the area just behind the choke, where the air cleaner sits). Gas was draining out of the hole that the air cleaner screw goes in. When I installed the air cleaner, apparently the same area would fill up with fuel but this time, it drained out the breather tube (insert explicative here). I removed the carb again and tried adjusting the float and needle valve to no avail.

Any idea what would cause this?

Also: I forgot to remove the the throttle blade and pin. I guess the carb cleaner ruined the seals on the pin as I had a little fuel seeping from that area. Any good suggestions on how to remove the throttle stop? It looks as if there's a tiny drive pin holding it on.

Any help is appreciated. This mower is about to get on my last nerve, lol. I only gave $100 bucks for it, so I can't complain too much. I need to do something quick though; as the grass is getting higher than I can bear to look at!

 
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04-18-09, 08:26 PM   #9  
The throttle shaft and valve shouldn't need to be removed unless there is excess play in them. The reason it's leaking from there is because the fuel level is too high in the bowl. The float could have gas in it, the needle needs replacing, and/or the seat is dirty/distorted. That's also why I asked if the oil smells like gas because generally when the carb needle leaks, gas gets into the crankcase and dilutes the oil.


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04-18-09, 08:42 PM   #10  
I'm thinking the float is ""Gas logged"" & isnt floating any more &/or the float needle has some trash in it,.. Check the oil for over full or a fuel smell & don't run the unit with fuel in the oil "till you fix it..You may only need a carb kit...Roger
Shake the float next to your ear & listen for sloshing inside, you said you dissasembled & soaked the carb & put it back together,,, Did you install a rebuild kit & clean every thing with compressed air & carb cleaner spray?? If you used the old parts & float that may be the problem,, Make sure you replace the needle & seat & double check the float....& as Cheese says, make sure there is no gas in the oil,, Maybe just change it anaway just to be safe.... Roger

 
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04-19-09, 05:28 AM   #11  
Thanks for the replies guys. A new needle valve and rubber seat came with the kit. I guess there's a possibility the seat could be distorted.

I'll check to see if the float is filled with gas.

 
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04-19-09, 02:43 PM   #12  
I disassembled the carb again and checked the float. The float still floats when submersed in gas in a small container; so I think we can rule that out.

After attempting to start it again, gas was still leaking from the throttle stop and throttle shaft. My B&S diagram shows a seal at either end of the throttle shaft. My guess is that the carb cleaner solution ruined these. I'm going to check with my local small engine shop and see how much these cost (more than I'd like I'm sure).

Aside from the gas leak, one would think that the engine would at least attempt to start. I couldn't even get it to fire at all. After a couple of tries I removed the spark plug and it was dry. After trying to start it numerous times, the plug was wet again. I know it's getting spark, air, and fuel, but for some reason it just doesn't want to start. The idle mixture screw and high speed screw are both set in approximate locations of where they were before disassembly. Again: you would think it would "hit" while cranking.

Ugghhh! This is getting frustrating. I'm the type of person who refuses to bring anything into the shop if I can fix it myself. If this carries on much longer, I'll have no choice but to load it up and carry it to someone who has time to go through it and diagnose everything.

My hopes are that I can replace the throttle shaft seals (and not be clumsy enough to lose that tiny drive pin for the throttle stop - just watch, it'll happen!), and crank and crank on it some more. I'm sure it's something miniscule that I'm missing!

Any input is appreciated.

Thanks in advance.

 
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04-19-09, 06:41 PM   #13  
You didn't change the seat?

We're all telling you what is wrong. As I said, the throttle shaft seals have nothing to do with any of this. The fuel level should never even get high enough to come into contact with the throttle seals anyway. If the fuel level gets that high, it is because and only because the needle valve is not shutting off the flow of fuel.

Did you shake the float near your ear to listen for gas sloshing in it as mentioned?


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04-20-09, 04:44 AM   #14  
Hi Cheese. Yes I shook the float and didn't hear any fuel inside. I replaced the seat as well when I initially rebuilt the carb (along with the needle valve).

The diagram that came with the rebuild kit showed that the float should sit parallel with the carb when closed with a caption reading "bend tab on float if necessary". I did have to bend the tab in order to get the float to sit level.

Is there anything I'm missing here? The seat looks to be installed properly. When I push the float up with my finger it "feels" as if its sealing the needle valve to the seat. That's why I'm so baffled by this. I'm under the impression I've covered all of the bases. Is there a trick to installing the needle valve and seat?

My apologies for the continuous questioning. I just want to get this right.

Thanks again.

 
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04-20-09, 07:08 PM   #15  
Does this carb have the very small "push-in" type seat??? Kinda like a fat "o" ring??? If so, I believe there is an in & an outside to them.. If it is this type, You were carefull not to scratch the carb when you pulled the old one?? (& didn't forget the old one in the hole??) Sorry about the last comment, but It's been done.. If you have a different style seat, Pleas ignore this post, Thanks, Roger

 
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04-20-09, 08:57 PM   #16  
I agree about the seat things Roger mentioned. One side of the rubber seat has a groove around it. This side goes down in the hole, leaving the non-grooved side facing the needle. Is that the way it was installed? Are you using the metal tipped needle or rubber tipped? If you have the rubber seat, then use the metal tipped needle (usually both are in the kit for these carbs). If the bore where the seat pushes in got scratched or has leftover pieces of the old seat in it, it will leak. If it got scratched, it may not ever stop leaking. You are right about the float setting...parallel to the carb body when upside down.


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04-21-09, 04:41 AM   #17  
Thanks for the replies guys. Yes it has the o-ring type seat and I did install it with the groove side opposite the valve. I also used the metal-tipped valve that matched my old one. I don't *think* I scratched the cylinder where the seat is located.

I talked to a guy that tinkers with small engines yesterday. He told me that if I hold the carb upside down (with the float in the closed position) and blow through the fuel line, air shouldn't escape. I tried this and sure enough, air didn't escape. This tells me that the valve is sealing properly. When I lifted the float, air flowed freely through the carb. The only thing I can assume is the problem is the float. I tried to diagnose it and "thought" it was fine. Apparenlty the float is not floating up enough to close the valve when the bowl fills with fuel.

I'll purchase a new float and try that.

Thanks again for all the help.

 
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04-21-09, 10:10 PM   #18  
If there is no gas in the float, it probably isn't bad. Check the bowl for dents in the side. Sometimes people tap the carb trying to stop it from leaking (unstick the float) and put dents in it. These dents can interfere with the float range of motion if they are deep enough.

I have had a hard time with some of these carbs doing exactly what you describe even after replacing the needle and seat. I have one at the shop now that seems to just keep seeping a little no matter what I do.


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04-23-09, 04:34 AM   #19  
Success! I buttoned everything back together for the millionth time and finally got her running. I made a few passes in the back yard and it ran great.

Thanks to all.

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